A remarkable species of the Dromiacea (Crustacea, Decapoda) from the Tsushima Islands

Among the crabs from the sea around the Tsushima Islands in the northwest of Kyushu collected by the research vessel 'Genkai ' for the trustees of the National Science Museum, Tokyo, a small curious crab was found. It is referable to the section Dromiacea on account of having the first pleopods in the female. After our close examination and the much consultation with Dr. I. Gordon and Dr. D. Guinot, the sole ovigerous female was proved to represent not only a new species but also a new genus. In the Dromiacea it bears some unusual features such as the absence of the vestiges of the uropods, the forwards position of the anterior margins of the third maxillipeds, the absence of the distinct linea dromiidica, the strong backwards extension of the abdomen bending at the fourth segment, and the flattened propodi and talon-like dactyli of the last two legs. Some of those features may be peculiar to the family Homolodromiidae, but the general formation of the carapace is more close to the family Dromiidae to which it is rather tentatively referred. In the following pages a new genus Genkaia named for the Genkai by which the Tsushima Expedition was carried out and a new species G. gordonae dedicated to Dr. I. Gordon in honour of the invalu-able contributions to the knowledge of the carcinology are described. The description may be, however, not always sufficient for getting the com